The present invention relates to an improved lever type control, such as a throttle lever control, for an internal combustion engine, such as the type of engine used in a riding lawn mower, to other engines which utilize a lever type of throttle control and to other units, such as a transmission control. The improved throttle control includes at least one throttle position which is preferred to be preset, which is easily detected in moving the throttle and which remains in the preferred position without throttle adjustments.
Prior control levers of the type considered herein have included many different configurations in an attempt to solve the many problems which are encountered but none of the prior art devices have included the combination of some type of mounting bracket or housing, a control lever, means for pivotally mounting the lever to the bracket or housing, means for connecting the lever to a control cable and the mounting means includes means to control the friction incident to the moving the lever between its positions.
One prior throttle control has introduced a washer around the pivotal mounting between the metal lever and the metal mounting bracket which was made of a material which is similar to a brake lining in an attempt to maintain a uniform friction between the lever and the mounting bracket. The pivotal connection also includes a rivet which extends through the lever, the washer and the mounting bracket and has a plurality of wave washers between the rivet head and the lever. The rivet is believed to be a shoulder rivet which extends through the wave washers, the lever and the washer and its shoulder abuts the surface of the mounting bracket and has its reduced end extending through the mounting bracket and formed against the opposite side of the mounting bracket. The mounting bracket includes two stops which are engaged by the lever at the respective ends of its travel and an opening which engages the end of the cable sheath. The lever includes an arm which engages the cable. The use of the friction material in this prior control did accomplish a unit in which the friction was controlled until it is exposed to an operator or to the environment. The application of a lubricant by the operator or the accumulation of grease and oil on the unit can drastically alter the amount of friction developed to resist the operation of the throttle. It is generally preferred that such friction cause a minimum of a 5 pound force and a maximum of a 15 pound force to move the lever.
Another prior throttle control utilized a similar metal lever and metal mounting bracket and a hard plastic material and a wave washer in the pivotal mounting and two stops on the mounting bracket at the extremes of the movement of the lever.
Another prior throttle control includes a metal mounting bracket pivotally mounting a metal throttle lever with openings in the bracket and a projection on the lever to ride on the surface of the bracket and engage within the openings as the throttle reaches such desired positions. The pivotal mounting includes a rivet with a wave washer biasing the lever against the bracket. This throttle relies entirely on the friction between the lever projection and the bracket. In many applications this friction may change drastically. For example, the accumulation of grease or oil and intentional lubrication of the surfaces can greatly reduce the friction and exposure to weather which causes oxidation of the surfaces of the bracket and lever can greatly increase the friction. The provision of the two selected positions which are other than in the throttle lever extreme positions is desirable.
Another prior throttle control utilizes the metal bracket and metal lever pivotally connected by a rivet with a plastic material between the lever and bracket and projections on the bracket and the lever which are adapted to coact to provide a stop in the lever movement. This control also includes a plastic washer between the rivet head and the lever and detents in the bracket in the area of the plastic material which appear to limit the movement of the plastic material between the bracket and the lever.
Another prior throttle control includes a plastic housing with a metal lever which is pivotally mounted within the housing and a serrated track which is engaged by the lever during its active motion to provide the desired friction. The movement of the lever past the ends of the track requires additional force but allows the extended movement of the lever in a friction free movement.
Another prior throttle control included a metal bracket and a metal lever with pivotal mounting of the lever and a friction washer between the lever and the bracket and another friction washer between the lever and a fixed metal washer with the fixed metal washer being secured to the bracket to prevent its rotation.
Additionally it is understood that washers have been used with throttle levers to control the force of movement of the lever wherein the washers have included facing serrated surfaces which require a certain amount of force to create the pivotal lever movement.